At present, mobile phone terminals provide no special security protection for key information on Subscriber Identity Module (SIM) cards, such as contacts, short messages, and the like; instead, those key information is just directly stored in the internal memories of the SIM cards. Data storage in the existing SIM card has the defect that no security classification is made for contacts in the card and all the contacts and short messages in the card are visible for all the users.
Therefore, there is a need for a new technical solution which may allow security classification for an SIM card so as to guarantee the security of data stored in the SIM card.